Sylvain Danto

• PhD
• Researcher at University of Bordeaux

Since the development of the first fibroscope in the late nineteenth century, the use of innovating glass fibers has opened promising perspectives for medical applications particularly in the domain of multimodal imagery[1]. In this work, tellurite glasses have been used to design step-index optical fibers with a rectangular core-section for superc...

Here, the direct incorporation of photochromic WO3 nanoparticles is investigated in a matrix of polymethyl methacrylate (PMMA) by bulk radical polymerization for the fabrication of plastic optical fibers (POFs). All the prepared composites, from preforms to 1D single fibers and 2D fabrics, are thoroughly investigated, leading to insight into their...

A novel type of waveguide Bragg grating (WBG) is demonstrated based on femtosecond laser-induced Type A refractive index modifications, namely based of the photochemistry of silver species in a specialty ortho-phosphate glass matrix. First-order WBGs are reported in the near-infrared and down to 736 nm in the visible. Relative transmission measurem...

Here, we report on core–clad bioactive borosilicate fibers, that we have prepared both with round and rectangular cross‐section profile. The exposed approach, which relies on the stacking and drawing of glass slabs, demonstrates our ability to develop bioactive‐based glass fibers with tailored cross‐section profiles. Tens‐of‐meters‐long fibers were...

In this paper, we investigate the WO 3-x /PVA composite films as smart photochromic coatings on glass substrate by two methods: solvent casting (SC) and dip-coating (DC). The two methods were thoroughly compared using experimental and theoretical means. All prepared films have been optically investigated by ex-situ and in-situ UV-Vis spectrometry,...

Gallium‐rich heavy metal oxide glasses have become highly attractive optical materials since they exhibit a wide transparency window spanning from the ultraviolet ∼270 nm up to the mid‐infrared (IR) region ∼6 μm making them promising for a future integration in optical fiber devices. Nonetheless, in most composition, surface crystallization is a ke...

The development of efficient and compact photonic systems in support of mid-infrared integrated optics is currently facing several challenges. To date, most mid-infrared glass-based devices are employing fluoride or chalcogenide glasses (FCGs). Although the commercialization of FCGs-based optical devices has rapidly grown during the last decade, th...

Herein, a tellurite multimode optical fiber with a rectangular step‐index core to combine easy coupling of the pump power with the exceptionally cubic nonlinearity of such type of glass is developed. An alkali‐free composition (TeO2–ZnO–La2O3) is prepared to produce a preform with the use of both the stack‐and‐draw and the direct‐bonding methods. T...

Here we present the ability of Nd ³⁺ -doped zinc-phosphate glasses to be shaped into rectangular core fibers. At first, the physico-chemical properties of the developed P 2 O 5 -based materials are investigated for different concentrations of neodymium oxide and core and cladding glass compositions are selected for further fiber development. A modi...

Here we explore the manufacturing of niobium-rich borophosphate glasses into fibers with optical quality. Glass preforms of composition [(100-x) (0.95 NaPO3 + 0.05 Na2B4O7) - x Nb2O5] with x = 37, 38, 39, 40 were synthetized and thermally drawn. Viscosity measurements performed in the softening point range show that the optical fiber drawing temper...

New Yb³⁺-doped phosphate glasses with a composition of (98.75-x) (90 NaPO3 – 10 Na2O) – x (Al2O3, TiO2, or ZnO) – 1.25 Yb2O3 (in mol-%), with x from 0 to 3, were prepared via conventional melting and quenching process. The thermal and physical properties were studied by differential thermal analysis (DTA) and density measurement, respectively. The...

A series of new transparent and magnetic barium gallogermanate glasses in the system (x) Gd2O3 – (100-x) [20BaO−15Ga2O3−65GeO2] with x = 0, 8, 14, 18, 22 and 25 mol% were synthesized. Their thermal, structural and magnetic properties were characterized. Based on the differential scanning calorimetry results, one determined the composition domain ex...

The radiation effects of electrons and protons on the spectroscopic and optical properties of oxide glasses doped with Yb 3+ in various glass systems were investigated to understand the impact of the glass composition on the glass photo-response. Changes in the optical and emission properties were seen after the radiation treatment, and the magnitu...

We report on the synthesis of transparent amorphous hydrated phosphate materials at low temperatures (as low as 300 °C) in the [50 P2O5 – (25 - x/2) K2O – (25 - x/2) Na2O – x ZnO] – n H2O (x = 0 – 25 mol%). These new transparent materials were studied by Raman and FTIR spectroscopies. The structure of the hydrated phosphates is proposed to consist...

Here we report on the effect of potassium or yttrium on the luminescence spectroscopic properties of Yb³⁺-doped germano-gallate glasses as well as the ability to shape them into optical fibers with the objective of using such glasses to produce near-infrared optical gain medium. Two ytterbium-doped germano-gallate glass systems, (100-x) (28Ga2O3 –...

In this work, 0%, 0.5%, 1%, and 2% Cu-doped WO3 nanoparticles were synthesized via a polyol method. The as-synthesized materials were characterized by x-ray diffraction, scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), x-ray photoelectron spectroscopy (XPS), and UV-Vis photochromic activity. A bond valence model was adopte...

The ability to produce robust fiber-based integrated optical systems operating over a wide spectral domain (UV to mid-infrared), is one of today’s key challenges in photonics. This work reports on the production of crystal-free, light guiding fibers from rich Ga2O3 oxide-based glass compositions. These materials show optical transmission extending...

Here, it is demonstrated that the stack‐and‐draw approach can be expanded to unusual materials association and profile geometries to generate fiber assemblies with unprecedented functionalities. This approach relies on the stacking of flat oxide glass slides into a preform, which is then thermally elongated into tens‐of‐meters‐long ribbon fibers wi...

Optical composite fibers based on active transition metal (TM)-doped semiconductor crystals are being investigated for use in mid-infrared (mid-IR) fiber laser systems. This study evaluates a candidate glass matrix system assessing its key physical properties and suitability for optical fiber drawing and examines the stability of TM-doped ZnSe crys...

Transparent fluorotellurite glasses were prepared by melt-quenching in the ternary system TeO2-Nb2O5-PbF2. The synthesis conditions were adjusted to minimize fluorine loss monitored as HF release. It was found that 10 mol% of Nb2O5 is the optimum content for PbF2 incorporation up to 35 mol% in the tellurite matrix without loss of glass forming abil...

We examine the thermal drawing of zinc tellurite silver-containing glass. While the silver-doped glass fibers remain unchanged over thermal drawing under oxygenatmosphere, we establish that under argon silver doping leads to the growth of a thin, metallic-like precipitate at the fiber surface. Optical, chemical and structural analysis, supported by...

Additive manufacturing of oxide glass enables on-demand, low-cost manufacturing of complex optical components for numerous applications, opening new opportunities to explore functionalities inaccessible otherwise. Here, we report a straightforward extrusion-based 3D-printing approach, deploying the fused deposition modeling (FDM) process, to produc...

This review focuses on the radiation-induced changes in germanate and tellurite glasses. These glasses have been of great interest due to their remarkable potential for photonics, in terms of extended transmission window in the mid-infrared, ability of rare-earth loading suitable with a laser, and amplification in the near- and mid-infrared or high...

Experimental development of a compact optical emission detector based on the assembly of a polymer-metal and a standard silica fiber is presented in this paper. This device is exploited in a proof-of-principle experiment for gas detection application by means of plasma spectroscopy in the visible-Near Infrared spectral region. A multimode fiber (MM...

Using femtosecond laser writing technique, near-surface waveguides with no need for additional processing were written in silver-containing glasses. An ultra-sensitive refractive index sensor exhibiting a novel double-wing feature is manufactured in a 1 cm glass chip.

Properties of the tellurite glasses 80TeO2–10ZnO–[(10−x)Na2O–xAg2O] are investigated as a function of the substitution ratio x between Na2O and Ag2O. One observe that the variation of glass transition temperature decreases monotonously with x and that surface crystallization mechanism is favored. The assignment of the Raman bands and their relation...

The generation of silver species has been investigated in silver‐containing sodo‐gallo‐phosphate glasses subjected to X‐ray irradiations. Radioluminescence spectroscopy has evidenced the presence of isolated and paired silver ions. The proportion of silver pairing is found dominant in ortho‐phosphate glass compositions, compared to poly‐phosphate c...

The femtosecond direct laser writing technique in glasses has been widely used and extensively studied during the last two decades. This technique provides a robust and efficient way to directly inscribe embedded 3D photonic devices in bulk glasses. Following direct laser writing, a local refractive index change (Δn) is induced that is generally cl...

Silver-containing glasses are promising candidates for photonic applications, due to the potentiality of spec-troscopic properties of silver nanoclusters (NC's) and/or silver metallic nanoparticles. In this framework, silver-containing fluorophosphate glasses are candidates with a strong potential. Indeed, combined with femtosecond laser irradiatio...

Here we report on the production of crystal-free light guiding fibers using a preform-to-fiber approach in the germano-gallate glass system Ga2O3-GeO2-BaO-La2O3-Y2O3 for various contents of gallium to germanium. For glasses in the system Ga2O3-GeO2-BaO-K2O, where surface crystallization precludes fiber drawing from the preform, an open-crucible tec...

Direct laser writing (DLW) of 3D embedded waveguides in glasses has been well established this last decade. However, few works of DLW of waveguides neighboring the glass surface were presented due to the ablation problems when getting near the glass surface. Some solutions have been presented like using reinforced glasses or using additional proces...

In the two last decades, development of more reliable femtosecond lasers has led to innovative laser/matter processes and key enabling technologies. Mainly applied to silica glass fibers, Direct Laser Writing (DLW) using femtosecond laser has been carried out to perform glass network photostructuration leading to many applications, including lab-in...

Silver containing glasses in the P2O5 - Ga2O3 - Na2O ternary diagram have been investigated to relate the effect of glass network structure and sodium ions concentration to spectroscopic and laser-writing properties of the materials. The first and most striking evidence is the large gain in the photosensitivity of fluorescent molecular silver clust...

Laser-induced glass processing has led to huge progress and applications over the last two decades. Here, we review recent advances in femtosecond laser-induced photochemistry in isotropic transparent oxide glasses specifically tailored with silver photoactive agents. The understanding of the influence of the considered glass matrix on the nature a...

Direct laser writing in glasses triggers three different type of refractive index changes classified as three types (Type I, II & III). In silver containing glasses, a novel type of refractive index change called type A has been reported allowing the creation of novel type of waveguides. Type I & Type A refractive index changes both could be trigge...

Direct Laser writing in silver containing phosphate glasses allows fabricating multi-scale photonic structures with various optical contrast (linear and nonlinear). The glass matrix composition determines the resulting photo-induced structures.

Direct laser writing in glasses is a growing field of research in photonics since it provides a robust and efficient way to directly address 3D material structuring. Generally, direct laser writing in glasses induces physical modifications such as refractive index changes that have been classified under three different types (Type I, II & III). In...

Tailored tellurite-glasses possess excellent thermo-viscous ability and linear/nonlinear optical properties. Here, bringing together the merits of these materials with fiber optic technology, we report on the first tellurite-based core-clad dual-electrode composite fiber made by direct, homothetic preform-to-fiber thermal co-drawing. The rheologica...

Tailored silver-containing zinc-phosphate glasses possess excellent thermoviscous ability and optical properties. Beyond they have proven to form a favorable matrix for the direct laser writing of photoluminescent and nonlinear patterns. Here, bringing together the merits of these materials with fiber optic technology, the first photosensitive, pho...

Infrared (IR) fibers offer a versatile approach to guiding and manipulating light in the IR spectrum, which is becoming increasingly more prominent in a variety of scientific disciplines and technological applications. Despite well-established efforts on the fabrication of IR fibers in past decades, a number of remarkable breakthroughs have recentl...

Multicomponent TeO2–Bi2O3–ZnO (TBZ) glass thin films were prepared using RF magnetron sputtering under different oxygen flow rates. The influences of oxygen flow rate on the structural and optical properties of the resulting thin films were investigated. We observed that thin films sputtered in an oxygen-rich environment are optically transparent w...

Thermal analysis techniques provide powerful tools for both the fundamental understanding and practical applications of chalcogenide glasses. Differential scanning calorimetry, thermogravimetric, and thermomechanical analysis all provide insight not only into those properties of chalcogenide glasses which are critical for hot-forming applications,...

This chapter covers state of the art in physical ageing of chalcogenide glasses. The thermodynamic origin of this phenomenon, experimental possibilities for its investigation, up-to-date results, general phenomenology and observed regularities are critically reviewed. The influence of various external factors, such as elevated temperatures, light e...

Organic polymer materials are widely credited with extreme versatility for thin film device processing. However, they generally lack the high refractive indices of inorganic semiconductors essential for tight optical confinement in planar integrated photonic circuits. Inorganic–organic hybrid photonic systems overcome these limits by combining both...

Photonic integration on plastic substrates enables emerging applications ranging from flexible interconnects to conformal sensors on biological tissues. Such devices are traditionally fabricated using pattern transfer, which is complicated and has limited integration capacity. Here we pioneered a monolithic approach to realize flexible, high-index-...

This paper reports a versatile, roll-to-roll and backend compatible technique for the fabrication of high-index-contrast photonic structures on both silicon and plastic substrates. The fabrication technique combines low-temperature chalcogenide glass film deposition and resist-free single-step thermal nanoimprint to process low-loss (1.6 dB/cm), su...

A high bandwidth density chip-to-chip optical interconnect architecture is analyzed. The interconnect design leverages our recently developed flexible substrate integration technology to circumvent the optical alignment requirement during packaging. Initial experimental results on fabrication and characterization of the flexible photonic platform a...

Chalcogenide glasses, namely the amorphous compounds containing sulfur, selenium, and/or tellurium, have emerged as a promising material candidate for mid-infrared integrated photonics given their wide optical transparency window, high linear and nonlinear indices, as well as their capacity for monolithic integration on a wide array of substrates....

High-index-contrast optical devices form the backbone of densely integrated photonic circuits. While these devices are traditionally fabricated using lithography and etching, their performance is often limited by defects and sidewall roughness arising from fabrication imperfections. This paper reports a versatile, roll-to-roll and backend compatibl...

In this article, we review our recent work on mid-infrared (mid-IR) photonic materials and devices fabricated on silicon for on-chip sensing applications. Pedestal waveguides based on silicon are demonstrated as broadband mid-IR sensors. Our low-loss mid-IR directional couplers demonstrated in SiN x waveguides are useful in differential sensing ap...

Photodetecting fiber. The fiber detects and localizes an incident optical beam. A semiconducting core is in intimate contact with a material forming a resistive channel that breaks axial symmetry. The resistive channel has a resistivity between that of metals and the semiconducting core, enabling the imposition of non-uniform, convex electric poten...

Long-wave infrared fibers are used in an increasing number of applications ranging from thermal imaging to bio-sensing. However, the design of optical fiber with low-loss in the far-infrared requires a combination of properties including good rheological characteristics for fiber drawing and low phonon energy for wide optical transparency, which ar...

We analyze a chip-to-chip optical interconnect platform based on our recently developed flexible substrate integration technology. We show that the architecture achieves high bandwidth density (100 Tbs/cm2), and does not require optical alignment during packaging. These advantages make the flexible photonics platform a promising solution for chip-t...

We experimentally demonstrated for the first time on-chip cavity-enhanced mid-infrared spectroscopic sensing of chemical molecules, performed near 5.2 μm wavelength using Ge23Sb7S70 resonators monolithically fabricated on CaF2 substrates.

Planar optical structures based on functionalized chalcogenide glasses provide a superb device platform for chemical and biological sensing applications. Chalcogenide glasses have demonstrated promise as materials for infrared sensing as they exhibit transparency over a large range of infrared wavelengths and tunable optical properties through dopi...

Here we show our ability to fabricate two-dimensional (2D) gratings on chalcogenide glasses with peak-to-valley amplitude of ~200 nm. The fabrication method relies on the thermal nano-imprinting of the glass substrate or film in direct contact with a patterned stamp. Stamping experiments are carried out using a bench-top precision glass-molding mac...

We have demonstrated what we believe to be the first waveguide photonic crystal cavity operating in the mid-infrared. The devices were fabricated from Ge 23 Sb 7 S 70 chalcogenide glass (ChG) on CaF 2 substrates by combing photolithographic patterning and focused ion beam milling. The waveguide-coupled cavities were characterized using a fiber end...

We demonstrated thermal nanoimprint fabrication of photonic devices in chalcogenide glass films on both semiconductor and nonconventional plastic substrates. A high micro-ring intrinsic quality factor of 3 × 105 is achieved at 1550 nm wavelength.

We demonstrated thermal nanoimprint fabrication of low loss waveguides and micro-ring resonators in thermally evaporated and solution processed chalcogenide glass films. A high micro-ring quality factor of 75,000 is achieved at 1550 nm wavelength.

We demonstrate monolithic fabrication of 3-D photonic structures on flexible substrates. Strain-optical coupling behavior of the flexible devices is quantified through in-situ optical measurements and is successfully accounted for using nanomechanical finite element analysis.

We fabricated and characterized high-index-contrast As2Se3 micro-disk resonators on silicon with a record loaded Q-factor of 105 at 5.2 μm wavelength. On-chip chemical sensing using cavity-enhanced infrared spectroscopy was demonstrated using the micro-disk device.

We fabricated and characterized high-index-contrast As2Se3 micro-disk resonators on silicon with a record loaded Q-factor of 105 at 5.2 μm wavelength. On-chip chemical sensing using cavity-enhanced infrared spectroscopy was demonstrated using the micro-disk device.

We demonstrated high-index-contrast, waveguide-coupled As 2 Se 3 chalcogenide glass resonators monolithically integrated on silicon fabricated using optical lithography and a lift-off process. The resonators exhibited a high intrinsic quality factor of 2 × 10 5 at 5.2 μm wavelength, which is among the highest values reported in on-chip mid-infrared...

Chalcogenide glasses, namely the amorphous compounds containing sulfur, selenium, and/or tellurium, have emerged as a promising material candidate for integrated photonics given their wide infrared transparency window, low processing temperature, almost infinite capacity for composition alloying, as well as high linear and nonlinear indices. Here w...

Chalcogenide glasses have been widely studied due to their extraordinary transparency in the mid-infrared region. Their transparency, combined with tailorable thermo-mechanical properties, makes them ideal candidates for various optic applications. Extrinsic impurities within the glass matrix can impede their integration in components where low opt...

Despite their unique attributes, extrinsic impurities within chalcogenide glasses (ChGs) can impede their integration in optical or photonic components where low optical loss is a criterion. The purification techniques currently in use for the manufacturing of low loss ChGs are both laborious and time consuming, often without yielding the desired u...

Thin film selenide glasses have emerged as an important material for integrated photonics due to its high refractive index, mid-IR transparency and high non-linear optical indices. We prepared high-quality As2Se3 glass films using spin coating from ethylenediamine solutions. The physio-chemical properties of the films are characterized as a functio...

Chalcogenide glasses, namely the amorphous compounds containing sulfur, selenium, and/or tellurium, have emerged as a promising material candidate for integrated photonics given their wide infrared transparency window, low processing temperature, almost infinite capacity for composition alloying, as well as high linear and nonlinear indices. Here w...

We report the fabrication and characterization of high-index-contrast AssSe3 chalcogenide glass waveguides on silicon. Guided mode optical transmission are measured at 5.27 μm mid-infrared wavelength with low optical loss.

Proton radiography is an imaging technique with potential application in proton radiation therapy. The ability of a proton radiograph to differentiate anatomical features in the thoracic region, such as heart, lung, rib cage, shoulder, etc., was qualitatively investigated using Monte Carlo simulations. A patient with a stage IIIA non-small cell lun...

Proton radiography imaging qualities have been studied using Monte Carlo simulations. A specific phantom, made of different common tissues, was implemented for simulations using the Massachusetts General Hospital treatment proton beam, pure 230- and 490-MeV proton beams, and a pure 100-keV X-ray beam. Along with spatial resolution, the signal-to-no...

We demonstrate the first rewritable memory in thermally drawn fibers. A high tellurium‐content chalcogenide glass, contacted by metallic electrodes internal to the fiber structure, is drawn from a macroscopic preform. An externally applied voltage is utilized to switch between a high resistance (OFF) and a low resistance (ON) state; this in turn al...

The synthesis of a high-melting temperature semiconductor in a low-temperature fiber drawing process is demonstrated, substantially expanding the set of materials that can be incorporated into fibers. Reagents in the solid state are arranged in proximate domains within a fiber preform. The preform is fluidized at elevated temperatures and drawn int...